1. Field of the Invention
The present invention relates to a shielding case from which a leader terminal is led out from a printed circuit board in a cabinet of high-frequency equipment such as a television tuner.
2. Description of Related Art
In a television broadcast receiving tuner, a circuit board on which circuit components have been mounted is housed in a cabinet, namely, a shielding case, constituted primarily by a frame, a top cover, and a bottom cover in order to shut out unwanted signals coming from outside and to prevent internal signals from leaking out.
FIG. 4 is a schematic representation illustrating a conventional shielding case.
FIG. 4 shows an example of the shielding case for a BS tuner, which shielding case is provided with: a square frame 3 which constitutes the peripheral side surface of the shielding case to compose open sections 1 and 2 which leave the top and bottom of the shielding case open; a top cover 6 and a bottom cover 7 which are fitted to the top and bottom edge sections 4 and 5 of the frame 3 and which respectively cover the open sections 1 and 2 of the frame 3; and a printed circuit board (hereinafter referred to as "PCB") 11 which is housed and installed in a space formed by a cabinet 8 composed by the frame 3, the top cover 6, and the bottom cover 7 and which is provided with inserting holes 10 in which molded base terminals 9 are inserted.
Such molded base terminals 9 are leader terminals; they may be, for example, metal terminals. The molded base terminals 9 or the metal terminals are employed to replace feed-through capacitors, which are high-frequency components. As illustrated in FIG. 4, when the molded base terminals (or the metal terminals) 9 are used, a side surface of the frame 3 is provided with an opening 12 through which the molded base terminals 9 are led out of the cabinet 8. The molded base terminals 9 are composed of metal terminals made integral with insulators 13 by insert or outsert molding.
Reference numeral 14 denotes an electronic component mounted on the PCB 11; reference numeral 15 denotes a PCB mounting plate formed on the frame by bending it; and reference numeral 16 denotes a PCB insert piece projecting from the bottom of the PCB mounting plate.
In the aforesaid prior art, however, since the molded base terminals 9 are led out through the opening 12 formed in the cabinet 8 (the frame 3), the opening 12 has been responsible for deteriorated shielding effect because the opening 12 is formed by eliminating the frame by a width L according to the number of the molded base terminals 9 installed. Hence, providing many molded base terminals 9 inevitably adds to the size of the opening 12 with resultant marked deterioration in the shielding effect.
At the time of assembly, the PCB 11 with the molded base terminals 9 fixed thereto by soldering is placed and installed in the frame through the top open section 1 or the bottom open section 2; since the distal ends of the molded base terminals 9 jut out from the left end of the PCB 11, the PCB 11 must be tilted to set it in the frame 3 such that the distal ends of the molded base terminals 9 are inserted in the opening 12 of the frame. This has been requiring complicated installing operation, making it difficult to achieve automated assembly.